text: Dr Nguyen Tri Dung, director of the HCMC Center for Disease Control (HCDC), said analysis of clinical factors and test results suggest that the person may be newly infected, with a currently unknown source of transmission?
classes:  No, doctors based their guesses to conclude that the man was newly infected, with an unknown source of transmission.  Also, doctors based their guesses to conclude that the man was newly infected, with an unknown source of transmission.  Yes, doctors based their guesses to conclude that the man was newly infected, with an unknown source of transmission.